The objective of this core is to provide complementary histopathologic and scientific support for the research projects by localizing proteins and/or mRNAs by immunohistochemistry or in situ hybridization in tissues and cultured cells. Dr. James A. Richardson will supervise the core. The core has an established history of expertise and competence in: 1) processing of tissues for routine paraffin embedding; 2) harvesting and flash-freezing of skeletal muscle and heart for cryotomy; 3) the standard histologic stains and special stains (Masson?s Trichrome, PAS, Feulgen) when required; 4) ATPase fibertyping and other enzyme histochemistry; 5) radioisotopic in situ hybridization; 6) maintenance of a library of murine embryos embedded in paraffin for analysis of developmental gene expression by in situ hybridization; and 7) bright-field, dark-field, phasecontrast, and epifluorescence microscopy and image analysis.